reduce amount query

app/controllers/home_controller.rb

@@ -6,7 +6,7 @@ class HomeController < ApplicationController
     @industries = Industry.order(name: :asc).all
     @job_count = Job.count
     @cities = City.all_cities
-    @lasted_jobs = Job.order(created_at: :desc).limit(Job::NUMBER_LASTED_JOB)
+    @lasted_jobs = Job.order(created_at: :desc).includes(:company, :cities).limit(Job::NUMBER_LASTED_JOB)
     @top_cities = City.top_cities(9)
     @top_industries = Industry.top_industries(9)
   end

app/controllers/job_controller.rb

@@ -19,7 +19,7 @@ class JobController < ApplicationController
 
   def render_result(obj)
     @keyword = obj.name
-    @data = obj.jobs.page(params[:page])
+    @data = obj.jobs.includes(:company, :cities).page(params[:page])
     render 'result_data'
   end
 end

app/models/city.rb

@@ -12,7 +12,8 @@ class City < ApplicationRecord
   scope :all_cities, -> { select :id, :name }
   scope :top_cities, ->(number) do joins(:jobs)
     .group(:city_id)
-    .order(Arel.sql('count(jobs.id) DESC'))
+    .select("cities.*, count(jobs.id) as job_count")
+    .order(Arel.sql('job_count DESC'))
     .take(number)
   end
 

app/models/industry.rb

@@ -7,7 +7,8 @@ class Industry < ApplicationRecord
   has_many :jobs, through: :industry_jobs
   scope :top_industries, ->(number) do joins(:jobs)
     .group(:industry_id)
-    .order(Arel.sql('count(jobs.id) DESC'))
+    .select('industries.*, count(jobs.id) as job_count')
+    .order(Arel.sql('job_count DESC'))
     .take(number)
   end
 

app/views/home/_box_nine_city.html.erb

@@ -12,7 +12,7 @@
               <%= link_to city.name, jobs_path(model: 'city', slug: city.slug),class: 'link_ct' %>
             </div>
             <div class="ct_jobs_count">
-              <%= link_to "#{city.jobs.count} công việc", jobs_path(model: 'city', slug: city.slug),class: 'link_ct' %>
+              <%= link_to "#{city.job_count} công việc", jobs_path(model: 'city', slug: city.slug),class: 'link_ct' %>
             </div>
           </div>
         </div>

app/views/home/_box_nine_industries.html.erb

@@ -11,7 +11,7 @@
               <%= link_to industry.name, jobs_path(model: 'industry', slug: industry.slug), class: 'link_ct' %>
             </div>
             <div class="ct_jobs_count">
-              <%= link_to "#{industry.jobs.count} công việc", jobs_path(model: 'industry', slug: industry.slug), class: 'link_ct' %>
+              <%= link_to "#{industry.job_count} công việc", jobs_path(model: 'industry', slug: industry.slug), class: 'link_ct' %>
             </div>  
           </div>
         </div>